Shifting Towards Offshore Wind Energy—Recent Activity and Future Development
Total Page：16
File Type：pdf, Size：1020Kb
Energy Policy 53 (2013) 136–148 Contents lists available at SciVerse ScienceDirect Energy Policy journal homepage: www.elsevier.com/locate/enpol Shifting towards offshore wind energy—Recent activity and future development J.K. Kaldellis n, M. Kapsali Lab of Soft Energy Applications & Environmental Protection, TEI of Piraeus, P.O. Box 41046, Athens 12201, Greece HIGHLIGHTS c An overview of the activity noted in the field of offshore wind energy is carried out. c Emphasis is given on the current status and future trends of the technology. c Wind energy production and availability issues are discussed. c Economic issues such as investment and energy production costs are also analysed. article info abstract Article history: To date, most of the existing wind farms have been built on-land but during the last few years many Received 10 February 2012 countries have also invested in offshore applications. The shift towards offshore wind project Accepted 11 October 2012 developments has mainly been driven by European energy policies, especially in north-west countries. Available online 21 November 2012 In offshore sites the winds are stronger and steadier than on-land, making wind farms more productive Keywords: with higher capacity factors. On the other hand, although offshore wind energy is not in its infancy Availability period, most of the costs associated with its development are still much higher from onshore Reliability counterparts; however some recent technological progress may have the potential to narrow this Levelized cost gap in the years to come. In the present work, an overview of the activity noted in the field of offshore wind energy is carried out, with emphasis being given on the current status and future trends of the technology employed, examining at the same time energy production and availability issues as well as economic considerations. & 2012 Elsevier Ltd. All rights reserved. 1. Introduction Up to now, wind energy development has mainly taken place onshore. Offshore wind power technology comprises a relatively During the last 20 years, many countries all over the world new challenge for the international wind industry with a demon- have invested in the wind power sector in view of facing the stration history of around twenty years and about a ten-year rapidly increasing population and the limited fossil fuel resources commercial history for large, utility-scale projects. In the end of along with the adverse impacts of conventional power generation 2011, worldwide wind power capacity reached 240 GW (WWEA, on climate and human health. Wind energy is currently consid- 2012), from which, 2% comprised offshore installations. The main ered as an indigenous, competitive and sustainable way to motivation for moving offshore, despite the low or even null achieve future carbon reductions and renewable energy targets impact on humans and the opportunity of building wind farms in but issues such as the scarcity of appropriate on-land installation coastal areas close to many population centres, stemmed from the sites or public concerns related to noise, visual impact, impact on considerably higher and steadier wind speeds met in the open birdlife and land use conflicts often block its future development sea, even exceeding 8 m/s at heights of 50 m. Compared to the (Esteban et al., 2011; Kaldellis et al., 2012). As a result, a onshore counterpart, offshore wind energy has greater resource substantial shift towards the vast offshore wind resources has potential, which generally increases with distance from the shore. been made and an incipient market has emerged, i.e. offshore This fact results to considerably higher energy yield (Pryor and wind power. Barthelmie, 2001), as the power output is theoretically a function of the cube of the wind speed. However, the net gains due to the higher specific offshore energy production are counterbalanced n by the higher capital, installation and maintenance costs and so Corresponding author. Tel.: þ30 210 5381237; fax: þ30 210 5381467. E-mail address: [email protected] (J.K. Kaldellis). the economic prospects of offshore wind energy utilisation are URL: http://www.sealab.gr (J.K. Kaldellis). not necessarily better than the onshore ones. 0301-4215/$ - see front matter & 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.enpol.2012.10.032 J.K. Kaldellis, M. Kapsali / Energy Policy 53 (2013) 136–148 137 As far as the technology employed is concerned, it should be In the following years, relatively small offshore wind power noted that the design of offshore wind power projects has been projects were installed in the United Kingdom, Denmark, the based considerably on the long-term experience gained from Netherlands and Sweden, at distances of up to 7 km from the on-shore wind farms and from the oil and gas industry, while coast and depths of up to 8 m. Multi-megawatt wind turbines the commercial wind turbines used, currently having capacity appeared later, along with the opportunity of experiencing deeper ratings up to 5 MW, comprise adaptations from land-based counter- waters in the sea. In 2000, the construction of the first large-scale parts. However, offshore wind turbine technology is evolving at a offshore wind farm of ‘‘Middelgrunden’’ with a total rated power fast pace and thus much larger machines are expected in the of 40 MW (20 wind turbines of 2 MW each) ended 2 km outside of foreseeable future, specifically constructed for offshore use, which the harbour of Copenhagen in Denmark, where the seabed is will likely benefit from economies of scale resulting in significant situated between 2.5 and 5 m under sea level. The demonstration cost reduction. project of ‘‘Middelgrunden’’ in Denmark led the way for two All the above issues are analysed in this work. More precisely, larger offshore wind power projects, i.e. Horns Rev I (160 MW) in the objective of the present study is to provide a short review of 2002 and Nysted (165.2 MW) in 2003. However, the construction the activity noted in the field of the offshore wind energy at a costs of these projects were higher than anticipated, while some global level, emphasising on global market issues, current status unexpected failures occurred, resulting mainly from the turbines’ and future trends of the technology employed, examining at the exposure to harsh wind and wave conditions. It was such draw- same time energy production and availability issues as well as backs that held back development of the offshore wind power economic considerations such as investment and associated costs market for a respectable time period (Fig. 1). Nevertheless, great of electricity generation. efforts made by manufacturers and developers in order to identify and improve problems associated with this stage (Musial et al., 2010) eventually led the way for a number of new commercial offshore wind farm installations, all located in European waters. 2. Global offshore wind energy activity The year 2010 was a record-breaking year for the European offshore wind energy market. New installations accounted for According to the existing literature, the first documented about 900 MW (Fig. 1) (which was about 10% of all new wind theoretical concepts for installing wind turbines at sea were power installations) (EWEA, 2011). As for the end of 2011, 235 developed in Germany in the early 1930s by Hermann Honnef. new offshore wind turbines, with a total capacity of about Almost forty years later, off the coast of Massachusetts, Professor 870 MW, were fully connected to the power grids of the UK, William E. Heronemus introduced the idea of large floating wind Germany, Denmark and Portugal. In total, as for the end of 2011, turbine platforms (Heronemus, 1972). None of these early visions there were almost 1400 offshore wind turbines fully grid con- became reality however. The first offshore wind power test nected with a total capacity of about 3.8 GW (Fig. 1) comprising facility was eventually set up in Sweden, twenty years later, in 53 wind farms spread over ten European countries. 1990. It was a single wind turbine of 220 kW rated power, located As of February 2012, the Walney wind farm in the United at a distance of 250 m from the coast, supported on a tripod Kingdom is the largest offshore wind farm in the world structure anchored to the seabed about 7 m deep. (367 MW), followed by the Thanet offshore wind project The first full-scale development of offshore wind power projects (300 MW), in the UK. The London Array (630 MW) is the largest was driven largely by commercial aspirations of the European wind project currently under construction which is also located in the industry, considering oceans as a feasible solution to compensate UK. In total, 18 new wind farms, totalling 5.3 GW are currently for the scarcity of onshore sites. The first commercial offshore wind under construction and 18 GW are fully-consented in twelve farm was commissioned in 1991 in Denmark, in shallow water European countries with Germany possessing almost 50% of the (2–6 m deep), 1.5–3 km north from the coast of the island of total consented installations (EWEA, 2012). Once completed, Lolland, near the village of ‘‘Vindeby’’. This small wind farm, which Europe’s offshore wind power capacity will reach 27 GW. is still in operation, consists of eleven stall controlled wind turbines Up till now vast deployment has taken place in Northern of total rated power 4.95 MW (450 kW each) all being placed on Europe, a situation expected to continue for the next few years as gravity-based foundations. The cost of construction for this project well. Actually, more than 90% of the global offshore wind farms is stated to be approximately 10 million Euros (SEAS-NVE, 2011).